MATLOUBI MOGHADDAM, FIROUZ, GHASEM REZANEJADE BARDAJEE, and HOSSEIN ISMAILI. 2010. “Synthesis of Bis(indolyl)methanes in Presence of Anhydrous Copper(II) Sulfate”. Asian Journal of Chemistry 20 (2):1063-67. https://asianpubs.org/index.php/ajchem/article/view/12528.